A magnetic disk device includes a magnetic disk arranged in a case, a spindle motor which supports and rotates the magnetic disk, a magnetic head which performs read/write of information on the magnetic disk, and a carriage assembly which movably supports the magnetic head with respect to the magnetic disk. A head portion of the magnetic head includes a magnetic recording head for writing and a reproducing head for reading.
There has been recent proposals for a magnetic head for vertical magnetic recording that enables a magnetic disk device having high recording density or large capacity and miniaturization of the magnetic disk device. In such a magnetic head, the recording head includes a main magnetic pole which generates a magnetic field in the vertical direction, a write shield which is arranged on a trailing side of the main magnetic pole with a write gap sandwiched between the main magnetic pole and the write shield and closes a magnetic path between the main magnetic pole and the magnetic disk, and a coil which supplies a magnetic flux to the main magnetic pole.
There has been also proposed a magnetic recording head for high frequency assist recording where a spin torque oscillator is arranged in the write gap. The spin torque oscillator is formed by laminating a field generation layer, an intermediate layer and a spin injection layer. In addition, the spin torque oscillator, the main magnetic pole and the write shield are electronically connected with each other.
In the magnetic recording head having the above-described configuration, a length of the write gap is defined by the total film thickness of the spin torque oscillator. On the other hand, to increase line recording density, that is, recording resolution in the track longitudinal direction, it is necessary to narrow the write gap. However, in the above-described configuration, it is not possible to make the write gap of the magnetic recording head equal to or smaller than a total film thickness of the spin torque oscillator and hence, it is difficult to increase the line recording density.